In this paper, we propose a non-contact ultrasonic liquid flowmeter based on AlN piezoelectric micromachined ultrasonic transducer (PMUT) arrays. Two 10 by 10 PMUT arrays with resonant frequency of 980 kHz in air are mounted outside of a pipe to measure liquid flow without contacting the liquid. An acoustic matching layer is designed to mitigate the loss of sound waves caused by sound reflection. Under excitation of continuous wave, the flow of the liquid can be determined via detecting the phase difference between transmitting and received signals. The measurement range of flow is 0.515 L/min ~ 3.40 L/min and the measurement error is less than 3%. Moreover, an interpolation method is proposed to reduce the signal sampling frequency without obviously affecting the measurement accuracy, which shows potential for further system integration.

中文翻译：

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基于AlN压电微加工超声波换能器阵列的小管道非接触式超声波流量测量


在本文中，我们提出了一种基于AlN压电微机械超声换能器（PMUT）阵列的非接触式超声液体流量计。两个 10 x 10 PMUT 阵列在空气中谐振频率为 980 kHz，安装在管道外部，无需接触液体即可测量液体流量。声学匹配层旨在减轻声音反射引起的声波损失。在连续波激励下，通过检测发射信号和接收信号之间的相位差即可确定液体的流量。流量测量范围为0.515 L/min～3.40 L/min，测量误差小于3%。此外，提出了一种插值方法来降低信号采样频率而不明显影响测量精度，这显示了进一步系统集成的潜力。